1. Field of the Invention
The present invention relates generally to a step ratchet mechanism that may be ideal for driving a multi-position device, such as an adjustable orifice. The step ratchet mechanism allows for the multi-position device to be moved a predetermined incremental distance each time the step ratchet mechanism is cycled. The movement of an incremental distance may allow the incremental opening of an adjustable orifice to pressure test the seals before completely opening the orifice. The distance the multi-position device is driven per cycling of the step ratchet mechanism may be modified by the adapting the physical dimensions of the step ratchet mechanism components as would be recognized by one of ordinary skill in the art having the benefit of this disclosure. The step ratchet mechanism may include a body lock ring or a body lock collet that locks the mechanism to a mandrel as the step ratchet mechanism moves during each cycle. The body lock ring or body lock collet may be adapted to also allow movement of the step ratchet mechanism in the opposite direction along the mandrel.
2. Description of the Related Art
The use of a body lock ring is a well known to lock a downhole assembly to a mandrel. Current body lock rings generally allow the assembly to travel along a mandrel in one direction, locking the assembly down to the mandrel each time the assembly stops moving. Body lock rings generally allow the assembly to be ratcheted along the mandrel in one direction, but typically are designed to lock the assembly to the mandrel and thus, do not allow the assembly to travel or ratchet in the other direction along the mandrel. This function of the body lock ring is often acceptable as the purpose of the body lock ring is to secure the downhole assembly to the mandrel. The current designs utilizing body lock rings do not allow the assembly to move along the mandrel in the opposition direction if so desired. If the downhole assembly needs to be removed from the mandrel, the downhole assembly and body lock ring may have to be drilled out of the wellbore.
The one-direction ratcheting nature of the body lock ring has limited its use to applications that only require movement in one direction. It would be beneficial to provide a device that ratchets or moves incrementally in one direction securing a downhole assembly to a structure such as a mandrel, but that also allows the downhole assembly to move along the structure in the opposite direction when so desired. For example, such a device may be useful in conjunction with a flow orifice. Downhole orifices are often used to regulate the amount of flow from a particular zone as excessive flow rates can cause formation damage or produce sand. Current body lock rings may be applicable to be used in such an instance. However, it would also be desirable to close the flow orifice if need be, which is not possible with current body lock ring designs. A device that allows incremental movement to open a flow orifice locking the flow orifice in place between incremental movements, but also while allowing movement in the opposite direction to also close the flow orifice would be beneficial.
In light of the foregoing, it would be desirable to provide a mechanism that provides for incremental movement in a first direction along a mandrel, secures an assembly to the mandrel, and also allows for movement of the mechanism in a second direction along the mandrel. It would be further desirable to provide a body lock ring that is adapted to both lock an assembly against a mandrel and also allow the body lock ring to release from the mandrel allowing the body lock ring and any connected assembly to travel along the mandrel. It would also be desirable to provide a mechanism that may be used to incrementally drive a multi-position device, such as an adjustable orifice, in one direction that also allows the movement of the multi-position device in the opposite direction while preventing movement of the orifice.
The present invention is directed to overcoming, or at least reducing the effects of, one or more of the issues set forth above.